Calendar watch indicator mechanism



Jan. 30, 1968 i Mier-uo SAWAMURA .3,365,876

l CALENDAR WATCH INDICATORy MECHANISM Filed Oct. 19, 1965 FIG. l

PRIOR ART PRIOR ART lNvENToR 7M SWW Patented Jan. 30, 1968 -1- CT OF T DISCLSURE Drive mechanism for a calendar watch wherein power is taken off the minute wheel to the date wheel to give a smoother power flow from the source of power.

Background This invention relates to a driving mechanism for the date indicator in calendar watches and in particular to driving mechanisms comprising an indicator driving member driven directly by the minute wheel or through a date wheel.

The primary object and advantage of this invention is to provide a date indicator driving mechanism capable of attaining exceptionally smooth movement.

Another advantage of the invention is that it is particularly useful for a cell Watch which is driven with a relatively small output by means of a reverse escapement which drives a gear train.

The invention and the conventional mechanisms may be better understood from the following detailed description of illustrative embodiments thereof, taken in connection with the accompanying drawings, in which;

FIG. 1 shows a plan view of the conventional mechanisms;

FIG. 2 represents a cross-sectional view through A-A of the same conventional mechanisms;

FIG. 3 shows a plan view of one embodiment of the invention; and

FIG. 4 shows a cross-sectional view through B-B of said embodiment of the invention.

Referring now particularly to FIG. 1 and FIG. 2, the feature which this invention has in common with many indicator driving mechanisms of the prior art is that it comprises a date wheel 4 which executes, at a calculated gear ratio, one revolution in 24 hours by the movement of an hour wheel 1 carrying an hour hand and through an intermediate date wheel 2 and a pinion 3 tted thereon. A linger 6 of an indicator driving cam 5 tted on the date wheel revolves either a star indicating Wheel, or a date ring 7 carrying 31 internal teeth 3. In the case of the latter, as the nger of the indicator driving cam slightly rotates the indicator ring, a date jumper 10 is oscillated against the force of a date jumper spring 9 until said date jumper passes the summit portion of an engaging tooth. Then said indicator ring is further revolved, by a distance corresponding to the remaining half pitch of the tooth, under the restoring force of the jumper spring which subsequently secures the ring, thus shifting the ring from one indicating position to the next one.

The basic difference between the indicator driving lmechanisms of the prior art resides in this, that in the prior art the hour wheel is driven through a minute wheel 13 which meshes with a cannon pinion mounted on the pipe of the hour hand, while the hour Wheel which drives the hour hand is loosely mounted on, and coaxial with, the

pipe of the minute hand. In these mechanisms, however, tilting of the pipes due to clearance between respective pipes and corresponding spacing creates a so-called overhung bearing situation, in which case, bearing sections receive an irregular binding pressure (particularly in the case where the date ring is employed), while a substantial side pressure is put on the delicate pipe of the minute hand, with resultant resistance adversely affecting movement of relative members.

The present invention permits an efiicient mainspring operation by decreasing friction and resistance in the drive train mechanism and thus increases duration of a given spring output and makes possible optimum characteristics of oscillation balance.

By contrast, as illustrated in FIG. 3 and FIG. 4, in the indicator driving mechanism of the present invention in a calendar watch in which pipe of minute hand 11 and pipe of hour hand (hour wheel 1) are coaxially provided, a minute wheel 13 which meshes both with cannon pinion 12 placed on pipe of minute hand 11 and with hour wheel 1 is provided in such a manner as to permit it to rotate an indicator driving cam 5 once every 24 hours, directly, or through an intermediate date wheel. 1S designates base plate and 16 designates a cover slate.

As the term pipe is used herein it is intended to indicate a tube adapted to support the hands of a Watch, gears, pinions, or the like, and being hollow a shaft or another pipe may operate inside of the first pipe As an eX- ample, pipe 11 as shown in FIG. 4 supports cannon pinion 12 in mesh with minute wheel 13.

By deriving the driving force for calendar Imechanism from pipe 11 of minute hand through minute wheel 13, both binding force which has been generated due to an overhung bearing condition of the pipe of hour hand, and side pressure on the pipe of minute hand which resulted from load on the hour wheel, are eliminated so as to minimize the resultant unnecessary resistance and make it possible to produce high precision calendar watches.

The described embodiment of my instant invention is, as has been stated, illustrative thereof, but not in any way restricted, and the invention is limited only as in the claim hereof.

What I claim is:

1. In a calendar watch having a cannon pinion on a pipe of a minute hand and a minute wheel and an hour wheel, the latter concentric with said cannon pinion, an annular peripheral date ring coaxial with the pipe of the minute hand of the watch, teeth on the inside of said ring, drive means for engaging said teeth and moving said ring one tooth each twenty-four hours, said means mounted on a rotatable gear wheel, a gear train from said gear wheel connecting it to a said minute Wheel which in turn is geared to said cannon pinion, and a gear ratio between said minute wheel and said rotatable gear such as to rotate the latter once in twenty-four hours permitting said drive means to move said date ring one tooth.

References Cited UNITED STATES PATENTS 3,036,424 5/ 1962 Perrot 5 8 5 FOREIGN PATENTS 9,298 1891 Great Britain. 16,964 6/ 1898 Switzerland.

RICHARD B. WILKINSON, Primary Examiner.

MICHAEL LORCH, Assistant Examiner. 

